Davit



A. I. DAWSON.

DAVIT.

APPLICATION FILED vJUNE 9, |920.

1,364,727. Patented Jan. 4, 1921.

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w/mfssfs INVENTO/f ATTORNEYS UNITED STATES ALBERT J'. DAWSON, OF PORTSMOUTH, NEW HAMPSHIRE.

Application filed June 9, 1920.

To all w71 omy t may concern Be .it known that I, ALBERT J. Dawson, a citizen of the United States, and a resident of Bortsmout'h, in the county of Rockingham and State of New Hampshire, have invented a new and Improved Davit, of which the following is a full, clear, and exact de scri'ption.

This invention relates to improvements in davits, and `more particularly to balanced davits, an object of the invention being to provide an improved construction of davit, mounting therefor, and operating means therefor, which result -in balancing the weight of .the boat so vas to reduce to a vminimum the power necessary7 to swing the boat from an inboard to an outboard position,

and vice versa.

A further object its to provide improved davits which can be quickly and eas-ily operated to move the lifeboats from :one posiw tion to another and provide a strong and durable support for the lifeboats so that they may be safely lowered to the water.

A further object is to .provide an imn proved Iconstruction and operating means for davits which may be utilized for other purposes than supports for lifeboats as the mechanism is capable of adaptation for transporting or moving loads from one position to another.

lith these and other objects in view the invention consists in certain novel features of construction, and combinations and arrangements of parts, as will be more fully hereinafter described and pointed out in the claims.

In the accompanying drawings Figure 1 is a view in transverse section through a portion of a ship illustrating in full l-ines my improvedconstruction of davit and Ioperating means, showing Ithe parts with the lifeboat in inboard position, .and in dotted .lines illustrating Aan intermediate position, and in ldot and dash lines a vfull outboard gposition.

Fig. '2 :is a view in side elevationof Fig. 1.

1 represents t-he hull Aof a `ship and in .the drawings I have illustrated but a fragment o-f the side of the hull at its point of attachment with the strengthening deck Q, and 3 is the boat deck located above deck 2 as is com-mon in the art.

4, 41, rel-present my improved dav-its which are pivotally connected .at their lower ends, asshown at 5, to brackets 6,1the latter fixed Specification of Letters Patent.

DAVIT.

Patented Jan. 4, 1921.

Serial No. 387,679.

to the hull 1 at its point of juncture with the deck 2 so that the strains of the davit are sustained by the hull structure.

In normal position the upper ends of the davits 4 curve inwardly and support levers 7. These levers 7 are made of two parts or of a single part connected by an integral pivot 8 which is mounted vto turn in the upper `end of the ydavit so that while the main or longer end of the lever 7 is on one side of the davit., the shorter end 9 of the lever is on the other side of the davit .and the shorter ends -of the two llevers lare located between the pair of davits and lprovided support for the lifeboat 10, said supporting means being indicated at 11 and constitu-tingthe ordi-nary arrangement of ropes and tackle as -is common Yin the art.

On lthe boat deck stringer 12 I provide any desired number of supporting brackets 13 in which a shaft 14 `has rotary mounting and lprov-ide on this shaft 11 a pair of crank arms 15 `having their free ends pivotally connected with the 'levers 7 by rmeans of links 1.6. rIhe links 16 a-re pivotally connected to the free vends of the arms 15 by means of pivot .pins or other suitable devices 17 and are pivotally connected to the levers 7 by pivot pins or'other suitable connections 18. Links 19 pivotally connect the pivot pins 17 with ,pivot pins 2O supported by -the intermediate .portions of the davits 4, 'as clearly .shown vin Fig. 1.

The shaft 14 may be turned by any suitable mechanism to control the operation thereof manually. 'I have illustrated as a .means for operating .this `shaft 141 a pair of intermeshing gears 21 and 22, the former fixed to .the shaft 14: and .the latter carried by a crank shaft 23 having a crank anm 24 to turn the same.

The operation is as follows: The load is supported from the free ends of 'the shorter members .9 of levers 7. When the Eshaft 14 is vturned in .the proper direction, it will cause the crank arms 15 to swing x.upwardly and outwardly. At `the saine time, 'through the medium ofthe links 16, this motion will l in F ig. 1. A continued movement of :the

shaft 14 in the same direction will move the parts to the position indicated in dot and dash line in Fig. 1, which will be the full outboard position ready for lowering the boat.

During the travel of the parts from one eXtreme position to another, it will be noted that the levers 7 are swung entirely around so that their pivot points 18 move in the arc of a circle approximating one hundred and eighty degrees, but the boat is carried in a comparatively straight path from one extreme position to another.

By virtue of the eccentricity of the load from a vertical through the pivot point 8, a counterbalancing force acting at the pivot point 18 is had, which is transmitted to the pivot point 17 by means of the link 1G. This rforce tends to revolve the cranks 15 in a counterclockwise direction. Now by vitrue of the load at theouter end of the members 9, this counteracting force at the pivot point 18 has a reaction at the pivot point 8, which, coupled with its eccentricity from a vertical through the pivot point 5, has a tendency to revolve the davit about the pivot 5 in a clockwise direction, which tendency is transmitted by the links 19 to the crank arms 15 at the pivot points 17. lVe have therefore two opposite forces acting on the cranks 15 at the pivot points 17 and in order to operate the davit, we have only to overcome the difference of the two forces plus the power necessary to overcome the friction of the bearings. In other words, the two forces have a balancing tendency, hence, I refer to my improved davit as a balancing davit.

The operation may also be described as a double or counterpoint toggle joint having one arm in common and being' acted upon by two forces having opposite components. During the operation of the davit, the vertical movement of the free ends of the lever members 9 is always opposite to the vertical movement of the pivot point 8 with the result that the boat moves in a straight or flat path which is the travel of the load, and there is also a slight vertical travel which means but a comparatively small total amount of work is done 'by the process of transporting the load from inboard to outboard position.

As the davits are pivotally connected to the strength deck of the vessel, or rather to the hull at the point of juncture with the strength deck, the strains and compression stresses are transferred directly to the hull proper and not to the lightly constructed boat deck as is common with davits in general use, and as the shaft 111 is located on the boat deck Stringer, the latter needs but little special foundation work.

It is obvious that the proportions of the several parts may be varied so as to describe different arcs or length of arc in movement,

and hence I do not wish to limit myself to the precise details set forth, but consider myself at liberty to make such changes and alterations as fairly fall within the spirit and scope of the appended claims.

I claim:

1. The combination with a ship, of davits pivotally connected to the ship, levers pivotally connected between their ends to the free ends of the davits, said levers adapted at one end to support a lifeboat, and a crank shaft operatively connected to the davits and also to the levers for moving the davits on their pivots and simultaneously swinging the levers on their pivots.

2. The combination with a ship, of davits pivotally connected at their lower ends to the ship at a point below the boat deck, a shaft supported on the boat deck, levers pivotally supported between their ends on the free ends of the davits and adapted to support a lifeboat at one end, crank arms secured to the shaft, links connecting said levers with the crank arms, and means connecting the crank arms with the davits.

3. The combination with a ship, of davits pivotally connected at their lower ends to the ship `at a point below the boat deck, a shaft supported on the boat deck, levers pivotally supported between their ends on the free ends of the davits and adapted to support a lifeboat at one end, crank arms secured to the shaft, links connecting said levers with the crank arms, and links pivotally connecting the crank arms with intermediate portions of the davits.

4. The combination with a ship, of davits pivotally connected at their lower ends to the ship at a point below the boat deck, a shaft supported on the boat deck, levers pivotally supported between their ends on the free ends of the davits and adapted to support a lifeboat at one end, crank arms secured to the shaft, links connecting said levers with the crank arms, and links pivotally connected at one end with the pivotal connections of the crank arms and the links and at their other ends pivotally connected to intermediate portions of the davits.

5. The combination with a ship, of davits, brackets pivotally connecting the lower ends of the davits with the hull of the Ship, other brackets located on the boat deck, a shaft supported in the last -mentioned brackets, levers fulcrumed between their ends on the free ends of the davits, said levers comprising two members disposed at opposite sides of the davits, crank arms on the shaft, links connecting the crank arms with said levers at one end of the latter, means on the other ends of said levers for supporting a boat, and links pivotally con-` brackets pivotally connecting the lower ends connecting the crank arms with said levers of the davits with the hull of the ship, other at one end of the latter, means on the other 10 brackets located on the boat deck, a shaft ends of said levers for supporting a boat, supported in the last-mentioned brackets, links pivotally connecting the crank arms levers uleruined between their ends on the with intermediate portions of the davits, free ends of the davits, said levers comprisand means for manually turning the shaft. ing two members disposed at opposite sides of the davits, crank arms on the shaft, links ALBERT J. DAWSON. 

